When catching fish to eat, proper handling of the fish is important, such as for safety and taste reasons. As fish are relatively delicate creatures, extended fighting and thrashing during capture can bruise the meat and stress the fish, thereby building up chemicals (e.g., lactic acid) that can make the meat taste sour and/or otherwise unpleasant. Moreover, after fish are caught, some people keep the fish on a stringer, in a mesh bucket, or in a livewell, typically until the fish dies or until someone is ready to prepare the fish. Such handling also can stress fish, leading to less palatable meat. Further, delaying the cleaning of a fish until long after its death may degrade the meat.
For the most palatable meat, fish should be stunned or killed soon after being caught. Doing so also removes the possibility of thrashing and biting, which could lead to lost fish, hook jabs, bruised flesh, etc. One technique for stunning or killing fish is to use a fish thumper (sometimes called a fish bat or a fish whacker), which is a baton, or similar device, used to hit the fish on the head to stun or kill the fish.
To further protect flavor and enhance storage life, fish may be bled soon after stunning or killing, typically by breaking or cutting the gill arch. Bleeding helps to eliminate from the flesh waste products that cause off-flavors (e.g., lactic acid), oxygen that leads to spoilage, and bacteria that lead to spoilage and/or contamination.
When landing a fish, it may be desirable or necessary to note the size and/or weight of the fish. The live weight of the fish is a useful measure of the size and may be obtained with a fish scale. For ease of handling, the fish weight may be measured after stunning the fish. To measure the live weight, the fish needs to be measured before bleeding, or any subsequent cleaning steps.
Aside from a fish scale and a fish thumper, landing a fish may involve use of several other tools, such as a fishing pole, fishing line, a net, a gaff, a knife, a hook puller, and/or a ruler. However, considering that many fishing sites are remote, requiring travel and/or hiking across significant distances, storing and carrying all these individual tools may be inconvenient, especially in the limited space of a boat or a portable toolbox. Hence, multi-purpose tools may be useful to those who fish.